The invention relates to a device and a process for mechanically grasping and setting down impact-sensitive plates of various formats on a stack arrangement such that they are ready for dispatch.
The production and sale of plates of various materials require special care when large and thin plates are involved. A particularly sensitive material in this respect is glass.
Despite the fact that it is taken for granted ubiquitously, flat glass processed to give window panes or auto glass is one of the most astonishing materials of our time. In contrast to hollow glass, it took several millennia longer until glass makers in the Middle Ages were able to produce flat glass panels that could be used for windows.
The most recent milestone in flat glass production was the development of the so-called float glass method in 1959. The novelty of the float method consists in the so-called “float ribbon”. This consists of molten tin. This tin bath is about 4 to 8 meters wide and up to 60 meters long. In this method, the liquid glass floats on the ideally flat liquid tin. When the glass mass is drawn from the melting furnace onto the tin bath, the tin is at a temperature of 1000° C. At the end of the tin bath, when the now solidified glass ribbon leaves the tin bath, the tin is at a temperature of 600° C. Tin is the only metal which satisfies the conditions required for this method: these are those of already being liquid at 600° C. and still not developing any disturbing vapor pressure at 1000° C.
After the solidified glass ribbon has been divided into the required formats after it has left the tin bath, the glass surfaces obtained in this way have to be stacked in order to be transported further.
DE-AS 1 259 783 discloses a device for depositing glass plates, panels or similar objects and picking them up again, said device having a latticed pivoting frame which uses its support bars to grip between rollers in a roller table when in a horizontal position. This pivoting frame can be pivoted out of its horizontal position about an axis which is placed horizontally on one side to the roller table and is perpendicular to the roller axes of the roller table, and, on the side which faces away from its pivot axis, this frame bears grippers for holding the objects. This device is substantially based on the object of depositing objects from the pivoting frame from a horizontal position on a roller table both in a horizontal position on a box and in a substantially vertical position on a stand laterally next to the roller table.
This object is achieved in DE-AS 1 259 783 in that at least one gripper chuck, which can be pivoted as a whole about an axis parallel to the pivot axis of the frame, is coupled to the pivoting frame as the gripper, the gripper jaws of this chuck being movable symmetrically in opposite directions in order to support the pivoting frame, and in that the pivoting frame has extension supports which are arranged in its plane and in parallel between its support bars and can be extended and retracted toward that side which faces its pivot axis.
Although this known device is also used to set down impact-sensitive plates on a stack arrangement, this process still takes place without the use of a multi-axis robot arm.
DE-AS 17 56 787 discloses a device for shifting glass panels between a conveyor and a bearing block on which the glass panels are stacked in upright fashion, in which essentially one supporting frame, which receives the glass panels to be stacked and has holding heads for the lower side of the glass panels, is arranged on a movable slide, wherein the holding heads can be deposited below the support plane of the glass panels. The object in this case is to provide a device for removing glass panels from stacks, which makes it possible to rapidly shift even fracture-sensitive glass panels, which are stacked on a bearing block, to a conveyor which receives the glass panels horizontally.
This object is achieved in DE-AS 17 56 787 in that the supporting frame is coupled, above its transverse center line, in a freely suspended manner on a frame support arranged on the slide, and a holding device which flexibly holds the supporting frame at a slight inclination counter to the inclination of the stacked glass panels is arranged between the frame support and the supporting frame and, when the holding heads are abutted against, permits a resultant pivoting movement of the frame beyond the perpendicular. Although the supporting frame in this case is likewise freely suspended, the glass plates are transferred substantially from the vertical position into a horizontal position. No gripping device in the form of a multi-axis robot is provided here either.
DE 10 2004 057 228 A1, as the closest prior art, discloses a process and a device for the high-speed stacking of plates, in particular glass plates, guided along a plate conveyor; this is based on the object of making it possible to stack plates of this type more quickly.